DS90UB926

Hi Dac,

Thank you for the answer.

I am in trouble to find the correct register settings for the I2C Downstream from a touch controller (400kHz).

Do you have an example ?

At the moment I work with your EvalBoards.

Best regards

Thomas

Hi Thomas,

On 926, registers 0x26 and 0x27 program the SCL High and SCL Low time respectively to adjust the I2C frequency. The default is about ~76kHz bus rate. So set 0x26, 0x27 =0x12 for ~400kHz.

Dac Tran

SVA APPS

Hi Dac,

Thanks for the bus rate settings.

The main problem is another:

To send I2C commands by FPD-Link from 925 to 926 works fine, but I couldn't receive any answers from the 926.

I attached a I2C slave at the 926 and I measured no signal at the SCL output Pin of the 926.

Best regards

Thomas

Hi Thomas,

Assuming your host is attached to 925, I2C communication to 926 will not be reflected on the remote 926 I2C bus unless you enable I2C pass all register 0x17 b[7] on 925. If you enable I2C Pass-through 0x03 b[3], then only the DES ID is used to access the 926. Can you provide your register configuration?

Dac Tran

SVA APPS

Hi Dac,

I send following Adr./Data to the 925:

03 FA; 04 00; 12 04; 17 8F

to the 926

03 BD; 04 FF; 05 8F; 06 00; 08 38; 10 38; 22 04

I can read the Data back from the 925, but from the 926 I didn't get an answer.

My Testsysten:

With this system and register setting, I couldn't measure a signal at the SCL Pin at the 926 deserializer Board.

Additional Question: On the EvalBoard schematics is a common mode choke, on the datasheet it isn't. What do you recommend ? 

Best regards

Thomas

Hi Thomas,

Let’s make sure the link is established before programming other registers. Start from beginning with default reg values. From factory settings on the EVM:

925 EVM ID = 0x18

926 EVM ID = 0x58

Make sure the 925 is connected to 926 and then power on. On 925, reg0x06 DES ID should be automatically loaded by the 926; which is 0x58 (0x00 is default). Next on 925, enable the passthrough bit on reg0x03 b[3]; or 0x03=0xDA. Now try to access the 926 with target address 0x58.

Dac Tran

SVA APPS

Hi Dac,

Just to be sure: if all works fine it should be possible to measure a I2C Clk at the pin 3 of the 926, and it is possible to have a standard I2C communication from / to a touch controller witch is connected at the 926 (like in the picture in some post's earlier.

At the moment it doesn't work, but I haden't tested your last answer.

Thank you very much for your support.

Best regards

Thomas Feller

Hi Thomas,

Note that any I2C addressed (from uC ->925) to the 925 (0x18h) or 926 (0x58h) will not show up on the 926 I2C bus. Enable pass-though register 0x03 b[3] and program both reg 0x06 SlaveID and reg0x07 SlaveAlias for the touchscreen slave address. Then any I2C addressed with touchscreen ID will be reflected on the 926 I2C bus. If pass-through is enabled on reg0x17 b[7], all I2C activity (regardless of reg0x06~0x07 value) is transmitted onto the 926 I2C bus.

Dac Tran

SVA APPS

Hi Dac,

I have developed our own system with the DS90UB925 / 926 (like in the sketch above).

All things works fine. On the I2C bus I have the touch controller, now I want connect a second I2C device to the the I2C bus. Is it possible to connect more than one I2C device to the DS90UB926? If yes, which are the values for the configuration?

Best regards

Thomas Feller 

Hi Thomas,

Yes, this is possible. However, each time the slave is about to be addressed, the 925 registers 0x07 and 0x08 (Slave ID and Slave Alias) must be loaded with the correct slave ID. 

Thanks,
Jason

Hi,

we have the proble that from time to time a lock failure does occurs.

In the datasheet we didn't found the the delay time value, from the point where the problem occurs, till the lock out does signaling the failure. This value would help for failure search a lot.

Please tell us this value.

Which circumstances could produce this Lock failure?

Thanks and best regards

Thomas